import React, { Component } from 'react'
// 1.导入withRouter函数
import {withRouter} from 'react-router-dom';

class Header extends Component {
   back = ()=>{
    this.props.history.goBack()
  }
  forward = ()=>{
    this.props.history.goForward()
  }
  go = ()=>{
    // 传递数字参数,正数n表示前进n步,负数n表示后退n步,
    this.props.history.go(-2)
  }
  render() {
    console.log('Header组件收到的props为:',this.props);
    return (
      <div className="page-header">
        <h2>React Router Demo</h2>
        <button onClick={this.back}>回退</button>
        <button onClick={this.forward}>前进</button>
        <button onClick={this.go}>go</button>
      </div>
    )
  }
}
// withRouter可以加工一般组件，让一般组件具备路由组件所特有的API
// withRouter的返回值是一个新组件,就是多了路由组件的api
export default  withRouter(Header)